Parking aids are known which warn the driver of a vehicle of objects which are too near to the front and/or rear of the vehicle. In such systems, proximity sensors are typically mounted in the front and/or rear bumpers. When an object is detected close to the front or rear of the vehicle, an audible alarm, typically a beeper, is sounded. As the vehicle gets closer to the detected object, the frequency of the beeper increases until the object is at a predefined distance from the vehicle, at which point a continuous alarm is sounded.
There are several problems with these known parking aids systems. When the vehicle is close to a detected object, a continuous audible alarm is sounded and the driver is not able to determine whether an actual collision is imminent. Further, in some situations, for example when simply passing objects which are very close to the front or rear side of the vehicle, a continuous warning is provided when there is no risk of collision. A further drawback is that traditional parking aid systems do not detect obstacles located to the side of the vehicle and therefore are not able to provide lateral collision warnings.
It is also known to provide a camera mounted on the rear of a vehicle and to display the image from the camera on a display screen on the dashboard of the vehicle. This allows the driver to view obstacles to the rear of the vehicle. It is also known to predict the trajectory of a vehicle based on the instantaneous steering wheel angle and superimpose a predicted trajectory path onto the camera picture on the display screen. This allows the driver to see, for a given steering angle, where the vehicle will travel. With such camera display systems, the driver must interpret the image on the screen in order to assess whether a given trajectory will result in a collision.